1. Field of the Invention
The present invention relates to a method and an apparatus for examining resistance of a plant to pathogen (or pathogenic microbe), a method and an apparatus for evaluating ability of a microbe (such as nonpathogenic strain or weak pathogenic strain) to impart pathogen resistance to a plant, and a method and an apparatus for evaluating ability of an agricultural chemical to activate pathogen resistance of a plant.
2. Related Background Art
The natural environment of Japan is suitable for growth of agricultural products, and on the other hand, also suitable for growth of pathogens or pathogenic microbe for various plants, such as molds (or mold fungi), bacteria and viruses. The prevention of disease due to such pathogens by pathogen-resistant varieties is very significant in view of a measure for reducing production cost of agricultural products, as well as health care (or health management) for humans.
As a method for examining the pathogen resistance or pathogen susceptibility (or sensitivity) of a plant, the following method has heretofore been used.
First, various pathogens are inoculated into seedlings or young plants to be examined.
Next, various symptoms caused in the seedlings by the above-mentioned inoculation, such as putrefaction (or rotting), spots, blight and wilting, are observed to examine the pathogen resistance and pathogen susceptibility of the plant.
This method is also used for screening a nonpathogenic strain or weak pathogenic strain capable of imparting resistance to a plant, or an agricultural chemical capable of imparting resistance to a plant.
However, this method has the following problems.
First, this method takes a very long time to provide examination results. In a case where a plant is bred without vegetative reproduction, the plant is generally grown from a seed. In this case, it will take about 3 weeks to grow a seedling from the seed, while it depends on the kind of plant. In addition, it takes about 1 to 4 weeks for a symptom to appear after various pathogens, agricultural chemicals, etc., are inoculated into the seedling. Accordingly, it takes at least about 1 to 2 months in total to obtain results in a case where the seedling is grown from the seed.
Second, the above method requires much labor and a vast site. A symptom appearing in the seedling varies depending on a combination of a plant, a pathogen and an agricultural chemical, and there is a large difference in the symptom between individual samples of the plant. Accordingly, for the purpose of statistic processing, it is necessary to cultivate a large number of samples of the plant. Thus, in order to cultivate such a large number of samples of the plant, much labor and a vast site are required.
Third, when the above method is used, the resultant symptoms appearing in individual seedlings cannot be measured quantitatively. In general, such symptoms are visually observed with eyes, and such visual observation largely depends on the experiences of observers, and much skill is required in order to obtain objective results.
Fourth, when the symptom is simply observed, it is difficult to recognize the internal state or condition in the inside of a plant. In order to recognize the internal state or condition of the plant, it is necessary to use a biochemical analysis technique, such as liquid chromatography and centrifugal method, for the purpose of measuring or analyzing various enzyme activities, specific protein peculiar to infection, etc. Such measurement requires much labor and a heavy monetary burden, and further requires a high-level technique.
Fifth, when the above method is used, it is very difficult to control the environment or ambient conditions under which the plant is to be examined. The resistance of a plant to a pathogen is highly susceptible to ambient conditions such as temperature, length of daytime, ultraviolet rays and visible rays. Accordingly, when samples of a plant are examined, it is necessary to place the samples to be examined under the same ambient conditions, However, when the above-mentioned conventional method is used, it is difficult to place the plants to be examined under the same ambient conditions.
Accordingly, an object of the present invention is to provide a method and/or apparatus for examining pathogen resistance (or pathogen susceptibility) of a plant, which have solved the above-mentioned problems.
Another object of the present invention is to provide a method and/or apparatus for evaluating an ability of a microbe (such as non-pathogenic strain and weak-pathogenic strain) to impart pathogen resistance to a plant, which have solved the above-mentioned problems.
A further object of the present invention is to provide a method and/or apparatus for evaluating an agricultural chemical which is capable of activating pathogen resistance of a plant, which have solved the above-mentioned problems.
As a result of the present inventors' study, it has been found that when a pathogen intrudes into a plant, and the plant reacts to the pathogen which has intruded thereinto, a change in ultra-weak luminescence is observed in accordance with the kind of the pathogen and the amount of the inoculation thereof. Based on such a discovery, the present inventors have developed a method and an apparatus which have solved the above-mentioned problems encountered in the prior art.
More specifically, according to a first aspect of the present invention, there is provided a method and an apparatus for optically examining pathogen resistance of a plant. According to a second aspect of the present invention, there is provided a method and an apparatus for optically evaluating an ability of a microbe such as nonpathogenic strain and weak-pathogenic strain to impart pathogen resistance to a plant. According to a third aspect of the present invention, there is provided a method and an apparatus for optically evaluating an agricultural chemical which is capable of activating pathogen resistance of a plant.
Japanese Laid-Open Patent Application No. 72802/1990 (Hei 2-72802) discloses a method for determining a condition of a plant by using ultra-weak luminescence. However, this method is one for determining degree of deterioration and germination potential of a plant seed. Accordingly, this method cannot solve the above-described problems.